Re: [PATCH v4 07/10] iommu/arm-smmu-v3: Allocate IOTLB cache tag if no id to reuse

Jason Gunthorpe
2026-04-10T00:05:10Z

On Thu, Mar 19, 2026 at 12:51:53PM -0700, Nicolin Chen wrote:
> An IOTLB tag now is forwarded from arm_smmu_domain_get_iotlb_tag() to its
> final destination (a CD or STE entry).
>
> Thus, arm_smmu_domain_get_iotlb_tag() can safely delink its references to
> the cd->asid and s2_cfg->vmid in the smmu_domain. Instead, allocate a new
> IOTLB cache tag from the xarray/ida.
>
> The old ASID and VMID in the smmu_domain will be deprecated, once VMID is
> decoupled in the vSMMU use case too.
>
> Since invst->new_invs->inv[0] and invst->tag are basically the same thing,
> merge arm_smmu_inv_flush_iotlb_tag() into arm_smmu_iotlb_tag_free().
>
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 63 +++++++++++++--------
> 1 file changed, 38 insertions(+), 25 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason